Process and apparatus for converting liquid substances into the form of granules



I Aug. 13, 1935. STEPHANSEN 2,010,902

PROCESS AND APPARATUS FOR CONVERTING LIQUID SUBSTANCES INTO THE FORM OFGRANULES Filed June 10, 1953 .Elg l III/III Patented Aug. 13, 1935UNITED STATES PROCESS AND APPARATUS FOR CONVERT- ING LIQUID SUBSTANCESINTO THE FORM OF GRANULES Nicolai Stephansen, Oslo, Norway, assignor toNorsk Hydro-Elektrisk Kvaelstofaktieselskab,

Oslo, Norway Application June 10, 1933, Serial No. 675,187 In NorwayOctober 1'7, 1932 3 Claims.

My invention relates to a process and an apparatus for the treatment ofliquid substances as melts, solutions,- emulsions or pulpy masses forthe purpose of solidifying the same and converting them into the form ofgranules.

Among the various kinds of apparatus used for converting liquidsubstances into the form of granules, rotating discs have been employedwith or without combination with heating means. By conducting thesubstances down on to .a quickly rotating disc in the near vicinity ofits centre, the substance is flung outwards, the water evaporated andthe mass converted into a more or less pulverized form, all according tothe 15 speed of rotation of the disc and the viscosity, quantity etc. ofthe substance. For instance, by this method mill; can be concentrated toa powder (dry milk) or concentrated salt solutions can be converted intosolid substances, .say niirate of lime or other materials.

When this method is to be used for producing ers in granular form, theproblem arises c ise large plants and apparatus capable of g hundreds ofthousands of tons per are. It is then either necessary to malre use agreat number of separate machines, or to everal discs on one axle. Aseach of the est have its separate supply of solutions d salt, theapparatus becomes very coms nce whereby it possible in one and the sameapparatus to obtain a manifold increase in I yield. The invention alsoaims at constructsuitable apparatus for carrying out the treatment,liquid substances in the form for in- 48 stance of a pulpy mass arespread over a rotatin; disc, so that the substance thereby gradual- 13;becomes converted into a very thin layer, the centrifugal iorce (rapidlyincreasing with the distance from the centre of the disc) wi l cause 45the layer or film formed to be broken up and so the mass becomes cakedbefore it leaves the disc. The aim. of the present invention is toprevent this. For this purpose I cause the film or flowing mass to bedivided into two separate parts 7 53 at a suitable distance from thecentre of the disc, it being as shall hereafter be more preciselydescribed, thereby possible to reduce the distance through which thelayer must pass before it leaves the apparatus, while at the same timeobtaining a layer or the necessary thinness.

More specifically described the process consists in dividing the film orflowing mass at a suitable distance from the centre of the disc intorays, so that outside of this point the mass is directed in two separateparts to another rotating part of the machine. These rays spread overthe rotating surfaces forming, before the mass leaves the disc, twoseparate films of a thickness corresponding to the peripheral speedwhich is suitable for the formation of an even product. 10

The process as above indicated will be fully understood by thedescription below the two forms of apparatus for carrying out theprocess.

Fig. l is a diagrammatic axial section of the simplest form ofapparatus.

Fig. 2 a similar drawing of a more complete apparatus.

Fig. 3 is a perspective view of a part of Fig. 1 on an enlarged scale,illustrating the manner in which the him of liquid material is dividedin two 09 sets of rays and thereupon led to form two separate films.

Figure 4- is a sectional view of the apparatus shown in Figure 1 showingthe means for heating the working surfaces.

In Fig. 1', A represents a driving shaft on which is fixed a centraldisc 33, shaped like a plate. Surrounding this is a larger disc C, whichin cross section has the shape of two cones united by a rounded portionas shown on the drawing and rotating with the central disc. On thisouter disc blades or shovels E, which alternatively lead to the upperand the lower part, are formed pointing towards the plate or disc B (seealso Fig. 3) The substance which is to be dried and granulated isconducted through pipe D down on the disc B. On account of thecentrifugal force, the mass is hung into the blades E on the outer discand the film is thereby cut into rays (F, Fig. 3), which is alternatelyconducted on the upper and lower surface of the disc C. These rays willspread on the surfaces of the disc C, and as they are getting thinner,they will unite and form a continuous film before they reach the edge ofthe disc, which latter they will leave in the form of powder orgranules. Fig.3 is seen from the axis of the apparatus a little distanceabove the central disc B.

G indicates a vertical, circular section of the film just before hittingthe blades E.

By giving the surfaces of the disc 0 a more or less conical shape theywill render more or less resistance against the action of thecentrifugal force and in this manner the apparatus may easily be adaptedfor the treatment of difierent substances.

Figure 2 shows how the efiect can be still further increased byconducting the substances from the central disc on to several paralleldiscs, both sides of these discs being used. This apparatus has an axleA, to which is fixed a central disc B. To this there is fixed orintegrally connected 8. ring R. Around this ring again there run twodiscs, C1 and C2, corresponding to disc C as shown in Fig. 1. When thesubstance is conducted through pipe D, it is flung out from disc B toring R, which is provided with blades as above described, that conveythe substance alternately up.

and down, to the upper or lower discs respectively. When the substanceleaves the ring R, the distribution takes place in exactly the samemanner as described above with reference to Fig. 1. In other words, theprocedure is repeated.

In such an apparatus there is only one supply pipe, which itis very easyto regulate. If the apparatus is used for pulverizing concentrated saltsolutions or melted salts or salts mixtures, the apparatus is as usualconstructed with a h0llow axle and hollow discs, so that it can beheated by warm water, steam or electricity.

In Fig. 4 the shaft A is shown hollow and having a central tube aconnected at its lower end with a channel 12 formed in the disc B andleading through a bridging connection d to the body C which is, in thisinstance formed with a closed hollow space 0. On the other side thisspace is through a channel e connected with the hollow space of theshaft A. The heating medium is introduced through the pipe a and passesthrough the channel I) to the space 0. and from th's through the channele back to the shaft, from where it goes to a heater and so keptcirculating through the apparatus. The particular means of heating theapparatus, howeverjforms no part of the invention.

I claim:

1. The process of treating liquid substance such as melts, solutions,emulsions or pulpy masses for the purpose of solidifying the same, whichconsists in first causing the liquid mass to be spread by the action ofcentrifugal force to form a continuous film, thereafter dividing thefilm into a number of rays, exposing said film rays to a successivelydecreasing resistance against its radial movement, while at the sametime the material is continually extended by the action of centrifugalforceuntil the mass is flungofi and left to free fall, during which lastperiod of the process the mass is solidified in the form of granules.

2. In a centrifugal apparatus, the combination with a central spreadingdisc and two annular resistance bodies the inner diameter of which isconsiderably greater than the outside diameter of the spreading disc,said annular resistance'bodies being disposed at an axial distance fromeach other on both sides of the central spreading disc, of an annularbody having greater inner diameter than the spreading disc and smallerouter diameter than the inner diameter of the aforesaid annular bodiesand being disposed in the space between said bodi'es so as to act as adistributor of the material from the central spreading disc to the saidannular resistance bodies.

3. In a centrifugal apparatus, the combination with a central rotatablespreading disc, of an annular body surrounding the same and taking partin its rotation, said annular body having surfaces which slope axiallyand radially along the path of movement of the fluid over said body, theaxial slope decreasing from the point at which the liquid strikes to thepoint at which it leaves said body.

NICOLAI STEPHANSEN.

